Locking shoe and mounting bracket for curl spring window balance system

ABSTRACT

A curl spring sash shoe cassette improves upon the suggestions of U.S. Pat. Nos. 5,353,548 and 5,463,793 by providing a mounting bracket that holds an uncurled length of the curl spring and is securely mounted on top of the shoe cassette to maintain an assembly of the shoe body, the curl spring, and the mount during shipment to a window manufacturer. The mount can receive two mounting screws to resist torque caused by curl springs and sash weight. The shoe is also improved to facilitate removal and reinsertion of sash pins into the tilt lock cams of the shoes and ensure that shoe body halves do not rotate relative to each other when sash tilting splays the body halves apart to lock them in a shoe channel.

FIELD OF THE INVENTION

Counterbalance systems for vertically movable window sash.

BACKGROUND

This invention improves on a locking shoe and mounting bracket usablewith a curl spring window balance system such as explained in U.S. Pat.Nos. 5,353,548, and 5,463,793. The invention adds convenience andreliability to the proposals of those patents.

SUMMARY

The improvements made by this invention include a mounting bracket thatcan hold its position while being shipped with a shoe cassette holding acurl spring and yet can automatically disengage from the spring shoewhen fastened to a sash jamb channel. The shoe cassettes are alsopreferably formed of identical halves that are unhanded so that a shoecassette can be deployed on either side of a window sash. The cassettehalves are preferably configured to resist relative rotation as they aresplayed apart in response to cam action of a tilt lock cam containedwithin the shoe. The tilt lock cams can be configured to retain headedsash pins, or can have recesses or slots that allow a sash pin to extendmore than half way through a locking cam. The improved system alsoallows locking pads to be inexpensively installed on the shoes to exertincreased locking friction when a sash tilts and shoe cams lock theshoes in their channels.

DRAWINGS

FIG. 1 is an isometric view of a shoe cassette including a curl spring,a spring mount, and a sash pin to counter balance one side of a windowsash.

FIG. 2 is an isometric view of a shoe cassette, including a curl spring,a spring mount, and optional locking pads to counter balance an oppositeside of a window sash.

FIG. 3 is a fragmentary view of an upper region of the cassette of FIG.2 omitting a curl spring to help illustrate a preferred configuration ofshoe mount.

FIG. 4 is a fragmentary cross-sectional top view of the shoe cassette ofFIG. 2 partially mounted within a shoe channel of a window jamb toillustrate how the shoe mount (in solid black) clears a tilt latch of asash.

FIG. 5 is a fragmentary rear view of the mounting bracket and the top ofthe shoe cassette of FIG. 2 to illustrate how the mounting bracketmounts on the shoe body.

FIG. 6 is an exploded isometric view of the cassette of FIG. 2 showing acurl spring, locking cam, and shoe halves, without a spring mount.

FIG. 7 is an exploded isometric view reversed from the view of FIG. 6 toshow that each shoe half includes a rotation resisting projection andrecess, and also showing a tilt lock cam with a through channel that canreceive a sash pin extending more than half-way through the cam.

DETAILED DESCRIPTION

Shoe cartridges or cassettes 10, such as illustrated in FIGS. 1, 2, 6and 7, include shoe bodies 11 that contain curl springs 30 and lockingcams 20. Shoe bodies 11 are preferably molded in halves 11a and 11b thatare identical and that fit together in an interlock allowing a lowerregion of the shoe bodies to expand or splay apart in response torotation of locking cam 20. Shoe body halves 11a and 11b are preferablyinterconnected at their upper regions by a pair of headed rails orridges that are formed on each of the body halves to slide into aninterconnect with the opposite body half.

An upper edge or top region 12 of shoe body 11 supports mounting bracket50. A short length of curl spring 30 is uncurled from shoe body 11 andis attached to mounting bracket 50, which can hold the assembled shoebody 11, curl spring 30, and mounting bracket 50 together for assemblyinto a window or shipment to a window manufacturer.

Mounting bracket 50 improves on a simpler bracket suggested in the '548and '793 patents. Bracket 50 is robust enough, and well enough bracedand interlocked at the top 12 of shoe body 11, to hold itself and curlspring 30 in place in an assembled cassette 10 during shipment. Thisprovides the convenience to a window manufacturer of shoe cassettesarriving assembled with mounting bracket 50 ready to secure eachcartridge in a shoe channel of a window jamb. All that is necessary isto slide each cassette into a shoe channel to the mount position, andthen drive in one or two fastening screws 51 to fasten mounting bracket50 in place. Two fasteners or mounting screws 51 are preferred so thatmounting bracket 50 can resist a torque or turning force applied by curlspring 30. In some jamb channels, mounting bracket 50 can be blockedfrom rotation by channel walls, making a single mounting screw 51 allthat is necessary for securely holding mounting bracket 50 in place.

To accomplish its improvements, mounting bracket 50 preferably includesmounting wall 52, spring holding wall 53, and brace 55, as best shown inFIGS. 3,4 and 5. Mounting wall 52 is preferably flat so that it can befastened snuggly against back wall 61 of shoe channel 60. Mounting wall52 also includes a hole 56 or a hole 56 and a slot 57 to receive one ortwo mounting screws 51. Spring holding wall 53 includes a projection 54oriented to fit into an opening 34 in curl spring 30, which exerts adownward pull on mounting bracket 50 to hold spring 30, mount 50, andbody 11 in the assembled position illustrated in FIGS. 1 and 2. Springholding wall 53 is preferably normal or perpendicular to mounting wall52, and brace 55 preferably extends normal or perpendicular to springholding wall 53 and parallel with mounting wall 55. Theinterrelationship between walls 52 and 53 and brace 55 cooperates withthe downward bias of spring 30, to securely support mount 50 on the top12 of shoe body 11.

The top or upper surface 12 of shoe body halves 11a and b preferablyinclude headed ridge or “dog bone” shaped connectors 13 that hold shoebody halves 11a and b together in proper alignment. Connectors 13 alsoallow a superposed attachment of an additional curl spring containermounted on top of shoe body 11. The headed rail connectors also providea sturdy interlock with mount 50, as shown in FIG. 5.

Mounting wall 52 preferably has an opposed pair of projections 85 thatextend under headed connectors 13 to prevent mounting bracket 50 frompivoting out of its position on the top 12 of body 11. The projection 85that is farthest from spring holding wall 53 is especially wellpositioned to prevent this. Spring holding wall 53 has a downwardlyextending projection 58 that overlaps with the adjacent dog boneconnector 13. Brace 55 rests on top of a connector 13, and has aprojection 59 (FIGS. 1-3) that hooks over an edge of the connector 13 onwhich it rests. All these features ensure that mounting bracket 50 staysreliably in place on top of shoe body 11, especially when curl spring 30provides a downward force pulling mounting bracket 50 downward againstthe top of shoe body 11.

Headed rail connectors 13 have end notches 14 that allow mounting wallprojections 85 to escape from under connectors 13 when mounting wall 52is fully attached flat against back wall 61 of shoe channel 60. In theposition of mounting bracket 50 as illustrated in FIG. 4, mounting screw51 has not been tightened enough to draw mounting bracket 50 snuglyagainst back wall 61 of shoe channel 60 so that mounting bracket 50 hasnot yet escaped from shoe body 11 via notches 14 in the ends ofconnector rails 13. Tightening screw 51 beyond the position illustratedin FIG. 4 to draw mounting wall 52 snugly against panel wall 61 thenmoves projections 85 into notches 14 of connectors 13, which allowsmounting bracket 50 to escape or separate from the top 12 of shoe body11. In practice, this separation occurs when shoe body 11 is pulleddownward after mounting bracket 50 is fully secured within channel 60.In effect, the sturdy interlock between mounting bracket 50 and shoebody 11 that allows shipment of assembled cassettes as illustrated inFIGS. 1 and 2 also automatically disconnects mounting bracket 50 fromcassette body 11 when mounting bracket 50 is fully secured in place in ashoe channel 60.

Since mounting bracket 50 is preferably free to slide along top surfaceof shoe body 11 when fastened into a shoe channel, as described, it isdesirable to allow relative movement between curl spring 30 and springholding projection 54. Relative movement at the interconnection betweenspring 30 and projection 54 allows mounting bracket 50 to slide intomounted position without pulling spring 30 laterally out of itsalignment with shoe body 11. A preferred way of accomplishing suchrelative movement is to make hole 34 in spring 30 an oval or oblong holeor slot, as best shown in FIGS. 6 and 7. Projection 54 can then movelaterally within oblong hole or slot 34 to leave spring 30 in itsaligned position relative to body 11 while mounting bracket 50 slideslaterally into a released position engaging wall 61 of a shoe channel.

As best shown in FIG. 6, locking cam 20 preferably has sash pin channelsor slots 22 arranged on opposite sides of an annular cam 21. Each of thecam slots 22 preferably has in turned walls 23 that can capture a head73 of a sash pin 70 (illustrated in FIG. 1). It is also possible, and ispreferred in some situations, for locking cam 20 to have a throughrecess or channel 25 that allows a sash pin to extend more than half wayinto locking cam 20 (shown in FIG. 7). A through channel 25 in cam 20allows a sash pin to penetrate deeply into cam 20 and is preferred toincrease the wind resistance of a sash.

Each body part 11a and b preferably has a recess 72 formed above the endregions of cam 20. When a sash supported by cassettes 10 is tilted outof the window plane, cam 20 turns to a locking position that aligns itschannel 25 or slots 22 with recesses 72. This allows the heads 73 ofsash pin 70 to be raised upward from cam slots 22 or channel 25 and intorecesses 72 to facilitate removing a tilted sash from a window.

Recesses 72 also facilitate replacing a removed sash, because recesses72 allow extra room above cam 20 to receive sash pin 70 that can then bedropped down into cam slots 22 or 25. Recesses 72 also provide asomewhat larger area for maneuvering sash pins 70 into shoe bodies 11aand b before dropping downward into cam channels 25 or slots 22. Thesash pins 70 can have heads 73 that interlock with cam edges 23 toprevent withdrawal of sash pin 70 from shoe cassettes 10 if a window iscarried in a suitcase fashion before installation. Sash pins 70 can alsobe un-headed and long enough to extend deeply into cam 20 for improvedwind resistance of a sash. The described arrangement of cam channels 22and 25, recesses 72, and sash pins 70 also allows shoes 11 to beunhanded, so that any shoe can be installed on either side of a sash tobe counterbalanced.

Mounting brackets 50, to the contrary, are preferably handed so thateach bracket is arranged to be mounted on only one side of a sash. Thispreference is to assure that mounting brackets 50 do not interfere withtilt latches of a counter balanced sash. FIG. 4 illustrates one way thatthis can be accomplished. Tilt latch 75, which is typically springloaded to be snapped into latching engagement with channel slot 62 whena tilted sash is moved back to an upright position, runs in slot 62 ofchannel 60 where it moves up and down with sash 50 to prevent accidentaltilting. When latches 75 are moved inward against their spring bias,they allow deliberate tilting of a counter balanced sash.

Brace 55 of mounting bracket 50 is preferably mounted in an orientationthat clears tilt latch 75 so that mounting bracket 50 does not interferewith vertical movement of tilt latch 75 past mounting bracket 50. Theleft- and right-handedness of mounting bracket 50 as identified by the Aand B markings appearing on mounting brackets 50 in FIGS. 1 and 2ensures that a mounting bracket on each side of a window sash clears thetilt latch 75.

Lower corners of body parts 11a and b preferably have molded recesses 82that can receive locking pads 80 or 81 to increase a frictional lockingeffect when a balanced sash tilts to pivot cam 20 to a locking position.Locking pads 80 and 81 (schematically shown in FIG. 2) are alternativesthat can be pressed into a recess 82 to achieve a pressed fit in recess82 for locking pad 80 or a snap fit in recess 82 for locking pad 81.Pads 80 and 81 can be surfaced with different materials and givendifferent surface configurations to increase the frictional security ofa shoe lock achieved by pivoting of cam 20 to spread shoe bodies 11a andb somewhat apart within channel 60.

When locking cam 20 pivots with a tilted sash, its cam surface 21 slidesin between lower edges of shoe bodies 11a and b to splay the shoe bodiesapart and lock the shoe cassette in place in a jamb channel. Thissplaying apart of the lower regions of shoe bodies 11a and b alsoproduces a force that tends to rotate the shoe bodies relative to eachother as they are forced apart by cam surface 21. Such rotation wouldtend to diminish the splaying apart of the shoe body halves, and thistendency is overcome by projections 15 and corresponding recesses 16that are formed in the lower region of each shoe half. As bodies 11a andb splay apart in response to rotation of cam surface 21, projections 15remain engaged with recesses 16 to prevent any relative rotation betweenshoe halves 11a and 11b. Recesses 16 can be formed as inward facingparts of recesses 82 whose outward facing parts can receive locking pads80 or 81. Projections 15 and recesses 16 are also preferably alternatelyformed on each body half 11a and b so that these halves remain identicalto each other while providing a pair of mating recesses 16 andprojections 15.

What is claimed is:
 1. In a window sash counterbalance shoe containing acurl spring disposed with curled convolutions in the shoe and anuncurled length extending to a bracket mounted on a top of the shoe tosupport the uncurled length of the curl spring during shipment, thebracket having a mounting wall disposed so that a mounting screw canpass through the mounting wall and secure the mounting bracket to a backwall of a shoe channel, the improvement comprising: the mounting brackethaving a spring holding wall normal to the mounting wall and disposed torest on a top surface of the shoe above which the uncurled length ofcurl spring extends; the spring holding wall and the uncurled length ofcurl spring being configured to interengage so that the uncurled springlength is held by the spring holding wall; the spring holding wallextending approximately for the width of the curl spring along an edgeof the top surface of the shoe so that the spring holding wall and themounting wall cooperate to resist a pull exerted by the uncurled lengthof the curl spring; and a brace extends normally from the spring holdingwall so that the brace engages the top surface of the shoe in a regionspaced from and parallel with the mounting wall.
 2. The improvement ofclaim 1 wherein the mounting wall of the bracket is formed with holes orslots to receive one or two mounting screws to prevent rotation of themounting bracket from spring force exerted during window operation. 3.The improvement of claim 1 wherein an interlock between the mountingbracket and the top surface of the shoe is configured to release themounting bracket from the shoe automatically when the mounting bracketis secured to a back wall of the shoe channel.
 4. The improvement ofclaim 3 wherein the spring holding wall has a projection engaged in alaterally extending aperture in the uncurled length of the curl springto allow the mounting bracket to move laterally of the shoe and the curlspring when the mounting wall is secured to the back wall of the shoechannel.
 5. The improvement of claim 1 wherein the mounting bracket isformed in right- and left-hand versions for deployment respectively onright- and left-hand sides of a sash to be counterbalanced so thatright- and left-hand tilt latches of the sash respectively clear theright- and left-hand mounting brackets.
 6. The improvement of claim 1wherein the top surface of the shoe has a pair of headed ridges, and themounting wall has opposed projections that interlock under the headedridges.
 7. The improvement of claim 6 wherein the headed ridges have endnotches that automatically release the mounting wall projections whenthe mounting wall moves laterally of the top surface of the shoe as themounting wall is secured to the back wall of the shoe channel.
 8. A curlspring counterbalance shoe and mounting bracket combination comprising:the mounting bracket having a mounting wall that in a shipping positionengages a top surface of a shoe containing curled convolutions of a curlspring; the mounting bracket having a spring holder wall perpendicularto the mounting wall and also engaging the top surface of the shoe inthe shipping position; an uncurled length of the curl spring extendingup one side of the shoe and along a face of the spring holder wall; theuncurled length of the curl spring being attached to the spring holderwall so that the mounting wall and the spring retainer wall each resista portion of the recurl force applied to the mounting bracket by theuncurled length of the curl spring; the mounting bracket beinginterlocked with the top surface of the shoe so that the mountingbracket, when attached to the curl spring, is retained on the topsurface of the shoe during shipment of the shoe, spring, and mountingbracket; and a brace extends from the spring retainer wall parallel withthe mounting wall so that the brace engages the top surface of the shoespaced from the mounting wall and helps support the spring holder wallagainst a force exerted by the uncurled length of the curl spring. 9.The combination of claim 8 wherein the mounting bracket is configured toreceive two mounting screws to retain the mounting bracket againstrotation during sash operation.
 10. The combination of claim 8 whereinthe mounting bracket is handed so that one configuration of the mountingbracket is arranged on a right side of a sash and an oppositeconfiguration of the mounting bracket is arranged on a left side of thesash, and the mounting brackets, when so arranged, provide clearance formovement of tilt latches on the sash.
 11. The combination of claim 8wherein the mounting bracket and the top surface of the shoe areconfigured to interlock during shipment and to release the mountingbracket from the shoe automatically when the mounting bracket is mountedin the shoe channel.
 12. The combination of claim 11 wherein the topsurface of the shoe has parallel headed ridges that interlock withopposed projections of the mounting wall, and notches in heads of theridges allow the automatic release of the mounting bracket from the shoewhen the mounting bracket moves laterally of the shoe during itsmounting to the shoe channel.
 13. The combination of claim 8 wherein theuncurled length of the curl spring has an aperture engaging a projectionon the spring holder wall, and the aperture is laterally wider than theprojection to allow the bracket to move laterally of the top surface ofthe shoe while the projection remains engaged within the aperture. 14.The combination of claim 8 wherein the mounting bracket is formed inright- and left-hand versions for deployment respectively on right- andleft-hand sides of a sash to be counterbalanced so that right- andleft-hand tilt latches of the sash respectively clear the right- andleft-hand mounting brackets.
 15. A curl spring shoe and mounting bracketcombination comprising: the mounting bracket in a shipping positionhaving a mounting wall interlocked with a top surface of the shoe; aspring retainer wall perpendicular to the mounting wall being orientedto align with a side of the shoe from which an uncurled length of curlspring extends upward above the top surface of the shoe; the springretainer wall and the uncurled length of the curl spring beingconfigured to interconnect so that the spring retainer wall holds andsupports the uncurled length of the curl spring above the top surface ofthe shoe during shipment; the interlock of the mounting wall with thetop surface of the shoe allowing lateral movement of the mountingbracket along the top surface of the shoe; the mounting wall interlockwith the top surface of the shoe being released when the mounting wallmoves laterally into engagement with a back wall of the shoe channelwhere the mounting wall is secured; and a brace spaced from and parallelwith the mounting wall extends perpendicularly from the spring retainerwall to engage the top surface of the shoe to help support the springretainer wall against a force exerted by the uncurled length of the curlspring.
 16. The combination of claim 15 wherein the mounting wall isconfigured to receive two mounting screws to resist rotational forceapplied by the curl spring.
 17. The combination of claim 15 wherein thespring retainer wall has a projection that fits into an oblong hole inthe uncurled length of the curl spring so that the projection can movelaterally within the hole when the bracket moves laterally to releasethe interlock with the top surface of the shoe.
 18. The combination ofclaim 15 wherein the top of the shoe is formed with a pair of headedrails, and the mounting wall is formed with a pair of opposedprojections interlocked under heads of the rails.
 19. The combination ofclaim 15 wherein end notches in the rail heads automatically release theinterlock with the mounting wall when the bracket is moved laterally forattachment to the back wall of a shoe channel.
 20. The combination ofclaim 15 wherein the bracket is formed in right- and left-hand versionsfor deployment respectively on right- and left-hand sides of a sash tobe counterbalanced so that right- and left-hand tilt latches of the sashrespectively clear the right- and left-hand mounting brackets.
 21. Acurl spring sash shoe cassette for a window assembly, the sash shoecassette comprising: a body defining a curl spring bearing surface, acam aperture, and a recess defined in a first surface of the body and bya ramped surface, said recess being adjacent and coupled to the camaperture at a first end of the recess, wherein the ramped surface isinclined from the cam aperture toward the first surface; a springrotatably disposed adjacent the curl spring bearing surface; a camrotatably disposed within the cam aperture, the cam defining a cam slothaving bearing walls, the cam being rotatable from a locked position tounlocked position, wherein the cam slot is aligned with the recess whenthe cam is in the unlocked position and not aligned with the recess whenthe cam is in the locked position.
 22. A curl spring sash shoe cassetteof claim 21 wherein the recess has a pair of sides which are generallyparallel to a travel direction of the window assembly.
 23. A curl springsash shoe cassette of claim 22 wherein the recess has an internalsurface generally perpendicular to the pair of sides.
 24. A curl springsash shoe cassette of claim 22 wherein the ramped surface is definedbetween the pair of sides.
 25. A curl spring sash shoe cassette of claim21 wherein the spring defines a coupling aperture.
 26. A curl springwindow balance having a shoe cassette configured to be positioned withina jamb channel of a window frame to facilitate the movement of a windowsash within the window frame along a longitudinal axis that extendsparallel to the jamb channel, the shoe cassette comprising: a bodycomprising a spring bearing cavity including a spring bearing surface, acam aperture with an axis generally perpendicular to the longitudinalaxis, and a recess in a first side of the body, the recess defined by apair of opposed first side walls and a ramped bottom surface, the recessadjoining the cam aperture at a first end of the recess, the rampedbottom surface being inclined away from the first end of the recesstoward the first side of the body; a curl spring rotatably disposedwithin the spring bearing cavity, the curl spring having an axis ofrotation perpendicular to the longitudinal axis; a cam rotatablydisposed within the cam aperture, the cam defining a slot between a pairof second side walls, the cam being rotatable from a locked position tounlocked position, wherein each of the second side walls is aligned witha corresponding one of the first side walls when the cam is in theunlocked position.
 27. A curl window balance of claim 26 wherein the camis coupled to a moveable locking member configured to engage the jambchannel.
 28. A curl spring window balance of claim 26 wherein the springdefines a coupling aperture.
 29. A curl spring window balance of claim26 wherein the ramped bottom surface is adjacent a second end of therecess opposite the first end.
 30. A curl spring window balance of claim26 wherein the opposed first side walls are generally parallel.
 31. Acurl spring window balance of claim 26 wherein the recess is furtherdefined by a surface generally perpendicular to the opposed first sidewalls.
 32. A curl spring window balance having a shoe cassetteconfigured to be positioned within a jamb channel of a window frame tofacilitate the movement of a window sash within the window frame along alongitudinal axis that extends parallel to the jamb channel, the shoecassette comprising: a body comprising a spring bearing cavity includinga spring bearing surface, a cam aperture with an axis generallyperpendicular to the longitudinal axis, and a recess in a first side ofthe body, the recess defined by a pair of opposed first side walls and aramped bottom surface, the recess adjoining the cam aperture at a firstend of the recess, the ramped bottom surface being inclined relative tothe first end of the recess and extending to the first side of the body;a curl spring rotatably disposed within the spring bearing cavity, thecurl spring having an axis of rotation perpendicular to the longitudinalaxis; a cam rotatably disposed within the cam aperture, the cam defininga slot between a pair of second side walls, the cam being rotatable froma locked position to unlocked position, wherein each of the second sidewalls is aligned with a corresponding one of the first side walls whenthe cam is in the unlocked position.
 33. A curl spring window balancehaving a shoe cassette configured to be positioned within a jamb channelof a window frame to facilitate the movement of a window sash within thewindow frame along a longitudinal axis that extends parallel to the jambchannel, the shoe cassette comprising: a body comprising a springbearing cavity including a spring bearing surface, a cam aperture withan axis generally perpendicular to the longitudinal axis, and a recessin a first side of the body being defined by a pair of opposed firstside walls and a bottom, the recess adjoining the cam aperture at afirst end of the recess, the bottom comprising a first bottom surfacebeing inclined away from the first end of the recess and extendingtoward the first side of the body; a curl spring rotatably disposedwithin the spring bearing cavity, the curl spring having an axis ofrotation perpendicular to the longitudinal axis; a cam rotatablydisposed within the cam aperture, the cam defining a slot between a pairof second side walls, the cam being rotatable from a locked position tounlocked position, wherein each of the second side walls is aligned witha corresponding one of the first side walls when the cam is in theunlocked position.
 34. The curl spring window balance of claim 33wherein the bottom further comprises a second bottom surface that isgenerally perpendicular to the opposed first side walls.
 35. The curlspring window balance of claim 34 wherein the second bottom surface isdefined between the cam aperture and the first bottom surface.
 36. Thecurl spring window balance of claim 35 wherein the opposed first sidewalls are generally parallel.
 37. The curl spring window balance ofclaim 36 wherein the first bottom surface extends to the first side ofthe body.